1. Field of the Invention
The present invention relates to an X-ray photography apparatus.
2. Description of the Background Art
Conventionally what is called intraoral radiography (dental radiography), in which X-ray a detection means (such as an X-ray film and an X-ray sensor panel) is set in the mouth cavity of a patient to photograph part of a row of teeth or a gum, is performed in X-ray photography of the dental field. Because only a local region is irradiated with an X-ray in the intraoral radiography, advantageously the photographing is simply performed and X-ray exposure is reduced. However, it is necessary to dispose in advance the X-ray detection means in the mouth cavity of the patient, and thus a large burden is placed on the patient.
Therefore, Japanese Patent Application Laid-Open No. 2007-136163 has made a proposal that panoramic photography is performed using a panoramic image photographing device and a tomographic image of part of the row of teeth or the gum is acquired using frame data obtained by the panoramic photography. In the panoramic photography, the X-ray is detected using an X-ray detector disposed outside the head of the patient. For this reason, the intraoral radiography can be performed in a pseudo manner while the burden on the patient is reduced.
For example, in the X-ray photography apparatus disclosed in Japanese Patent Application Laid-Open No. 2007-136163, a suitable gain (a shift amount in the case of shifting and adding frame data) is previously defined by a look-up table in each position of a region of interest. Therefore, the X-ray photography apparatus acquires the gain corresponding to the designated region of interest from the look-up table and, by shifting and adding the frame data according to the gain, generates one tomographic image. Therefore, in the conventional X-ray photography apparatus, only one type tomographic image is generated for a specific tomographic plane, and diagnostic information on part of the row of teeth or the gum is limited.